


Knot for the Faint of Soul

by FortnightofSin



Category: Undertale (Video Game)
Genre: Breeding, Excess Cum, F/M, Impregnation, Knotting, Minimum Soul Sex, Soul Bond
Language: English
Status: Completed
Published: 2016-08-29
Updated: 2016-08-29
Packaged: 2018-08-11 17:43:45
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,479
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7901857
Author URL: https://archiveofourown.org/users/FortnightofSin/pseuds/FortnightofSin
Summary: <blockquote class="userstuff">
              <p>With all the new monster/human relationships came the discovery that while shocking, was not all that surprising.</p><p>Humans and monsters could have children.</p><p>And that was exactly what you had planned for tonight.</p>
            </blockquote>





	Knot for the Faint of Soul

**Author's Note:**

> Pure porn, I severely needed a breeding fanfic to indulge myself. Haven't written porn in a while so tell me what you think of it.

You had just gotten out of the shower and wrapped a big fluffy towel around yourself as you checked the reflection in the mirror. Wet hair hung in thick locks and clung to your face.  Brushing them back reveals two eyes full of color and excitement. Tonight is the night you think to yourself, drying off, the night you and Sans had planned for quite some time ago.

When monsters had been announced on the surface, everyone was shocked. Who knew there had been such amazing creatures buried just below the rock of Mt. Ebott? As the monsters fanned out across the world, a certain skeleton had capture your soul with bad puns and good times. The two of you had eventually bonded, the ultimate sign of affection and trust between two people. It had been strange, but always endearing how Sans would fumble through your human dating customs and he would agree, thinking about your enthusiastic attempts at monster romance. It was an enthralling and lascivious adventure filled with magic and other dopey emotions, and the bond you two shared was proof of that. At first your relationship had been fairly taboo, but as time went on, more and more people became happily bonded with monsters. To the extent it was no longer a hush-hush affair. With all these newfound relationships however, came the discovery that wasn’t so much as surprising but shocking all the same.

Humans and monsters could have children.

And that was exactly what you were planning for tonight.

Anticipation warmed your chest and coiled lowered, already dampening the panties of your chosen lingerie. You’d bought it specifically for this occasion and hummed at the thought of them being torn to shreds by the end of the night. Your soul gave a warming pulse and was immediately greeted with another. Swelling with the feelings of urgency and expectation, pulling you toward the bedroom where your boney lover awaited you. Hair dried and towels abandoned, you opened the door.

Soft light meet your eyes as you stepped out of the bathroom, bare feet silenced by the plush carpeting. Sans was perched tensely at the end of the bed, but drew his eyes to your form as the door creaked and betrayed your approach. His pinpricks of light were sharp, focused. Eye sockets widened in a moment of shock as a brushing of blue made its way onto his zygomatic arches. The notion that you could still stun him after all these years filled you with confidence, which let a coy smile of invitation twitch across your lips.

He’d caught it to, not only in your change of expression, but within your soul as well. He stood and stalked his way toward you, eyeing you with such predatory emotion. That look sending pleasant chills down your spine as you stood your ground. He circled, taking you all in but he kept his hands to himself. The air crackled with the intensity of Sans’s magic, powerful yet well contained.

“My, my, what a lovely outfit. Did you wear it just for me?” He stares unabashed at your curves, while you fidget under his scrutiny.

The brush of his jacket teases you with the delicate feeling as he stepped close, still refraining from touching. You were no longer smiling, a furious blush made its way onto your cheeks and you sucked in a breath, holding it. Senses on overdrive, whole body tense and quivering from anticipation as you closed your eyes. His musky scent, the sparks of magic, his physicality. The entirety of his presence washed over and overwhelmed you. Hormones flared into life at his proximity. You were his. The thought of being utterly claimed by your monster of a mate sends torrents of heat to your core. Body and soul both ached for his touch, his voice, anything to break this delicious tension.

He felt it too, the pulse of need from your soul through the binding link between you. Never in Sans’s life had he thought he’d be so lucky, perhaps it was fate’s way of compensating for all the shit he’d gone through Underground. Regardless of what you’d call it, the fact that you had bonded with him still sends him into that possessive protectiveness and every time you call to his soul, bursting with desire, it awakens something primal within his being.  He reaches up around you and sets his phalanges on your hips slowly, one finger at a time.

His hands trail softly up and down your sides, feeling your soft curves, your yielding flesh. The growl that escapes him sends goosebumps down your spine that have nothing to do with fear. He can’t take it, he needs you close to him.

Suddenly pulled flush against San’s torso, a gasp escapes you. He grips you tightly as one hand trails upward to grab your jaw and tilt your head. He inhales, thick arousal wonderfully taints the sweetness of your natural scent and it, coupled with the now exposed skin of your neck, makes his mouth water.

“Fuck you’re beautiful,” he states. He rubs his thumb across your lips, feeling their softness.

“All dressed up for me,” He nips at your ear. “You’re already wet for me aren’t you,” He laps at your neck, “and I haven’t even done anything to you yet.” You start to shake in his embrace, mind going foggy.

“I’m so lucky to have such a submissive mate, always willing to take what I give her.”

You whine in response. You loved it when he talked like this, reminding you of your place as his mate. Explicitly saying that you were bringing pleasure to a _monster._ That it was your duty to please him. Not that you didn’t have power over this, quite the opposite. He came to you for satisfaction, to take gratification from your body, to take solace from your soul. And you had every ability to give it, or take it away. Not that you wanted to, but you prided yourself on being able to please him, and that kind of power was addicting. It drove Sans mad telling him you wanted, craved, his ministrations. Your egos were reinforced by your own partner’s pleasure.

As you lost yourself in compliments, his hand moved down to your breasts and squeezed one firmly. You wiggled in his grasp and grinded your ass into his pelvis, trying to strangle the sounds clawing up your throat, hoping he’d get the message. You were on a mission tonight, to cement your bonding in a physical manifestation. To completely combine in body, soul, and magic.

He grinned, such was like you, desperate for attention yet too stubborn to admit it. He needed to hear it though. He knew what you wanted, you two had planned this after all, but that begging, pleading pulse from your soul would be the final push to allow him to give into his barely contained desire. Magic pulsed wildly in his bones and his left eye was sparking with it.  A little coaxing would be all it’d take as he played with your stiffening peaks barely hidden by the lacy fabric of your top.

“Saaaaaans” you moaned and arched into his touch. He had to grind his teeth to keep himself in check, his magic already gathering in his pelvis, urgently rubbing against your backside. His bones rattled, god did he want you, such a beautiful creature. His friend, his lover, his MATE.

“Aaah…”

“Please,” he groaned, “what should I do to you?” He brought his hand up from your hip to rest encouragingly on your belly, palming the soft skin underneath.

“Sans…” His body tensed, your hands clutched desperately at his jacket, and panted out your response. “P-please… breed me!”

 

With an eruption of power, a cocoon of blue magic encased your soul and flung your body against the bed. Magic so familiar that you knew no harm would come from such an action, yet the vulnerability that Sans had ahold of your very essence was intoxicating. You didn’t have much time to debate it as Sans was soon to follow, hovering right above you as you landed on your back. Immediately, he attacked your neck with nips and kisses that were sure to bruise in the morning as he kept you in place beneath him by wedging himself between your thighs. You keened from his attention and tugged at his shirt, wanting to grasp at his ribs. He obliges by tugging it off and chucking it across the room. You splay your hands out across his cage, feeling how utterly solid he was and hummed out your appreciation.

He trailed his way down your neck to your collar bone and stopped at the valley between your breasts. Concealed by the garment you were wearing. He growled and mumbled “in the way” as a rip sounded through the room, exposing you. The eager action sent warmth straight to your belly. He went on to capture one perked nipple between his teeth. Your arms remained trapped between you two, but you clung to his ribs which made him rumble happily. He hungrily laps at your skin, the blue magic sparking coolly, leaving wet streaks. High pitched squeals and mewls escape your lips which are quickly swallowed by the domineering skeleton as he ravages your mouth, his hands never leaving your form.

As you break the kiss for air he quickly flips you onto your stomach and roughly pulls your ass up in the air. The question flows through your soul link as to your position. Sans replies, “Are you sure humans can’t go into heat babe? Because you’re sure acting like it.” The statement only serves to pull you further into your lust induced haze. “A bitch begging to be bred, it only makes sense to fuck you like one.” You moan as you watch Sans bite into the lacey fabric covering your core and again rip it away to get to his prize. He has no trouble delving two boney fingers into your muff, spreading his hand to rub your clit. You shiver in appreciation, enjoying every bump and ridge of his phalanges. All too soon he removes it leaving you to whine in dismay, but it catches in your throat when something larger, thicker, and ultimately more satisfying lines itself up with your entrance.

He hovers over top of you and you rock back into him as he teases you. He’s shaking with restraint but still manages to ask, “You ready hun? Ready to be fucked by your _monster_ of a mate?” Of fucking course, making puns at the most opportune times.

“Sans, please” you beg. And at that your souls call out to each other both sparked by desire and neither one can hold back. In one fluid movement he slides into your warmth, both moaning from each respectively pleasant feeling. No words are said as he begins to thrust, slowly at first, reveling in the pull of your walls trying to keep him inside, as sweet noises erupt from your mouth.

_“More!”_

You cry out for him. It feels so good, to be filled, to be under his strong form. The rhythmic smack of bone on yielding flesh, your silhouettes painted in shadow on the wall, his hot panting on your shoulder blades. The eroticness of it all only adds to the accumulating heat in your loins. Each time Sans enters you he rams the tip of his cock against your cervix, making you see stars. You grasp the sheets desperate for something to ground you. Sans clutches at your waist as his hands rake upwards to grasp at your breasts. The weight of him pushes you down onto your forearms thoroughly keeping you pinned underneath him.

_“As you should be.”_

Sans has lost himself in the moment. You wanted a child, HIS child. You wanted him to cum inside of you with a purpose, to fertilize. The bond you two shared hid nothing of your intentions, you needed him inside you, to make you utterly his in every way. To claim you so intimately that you’d be forever marked as his. You would only yield to him, only make those wonderful sounds for him. Scream his name in pleasure drunken praises. Something primal from within his soul awakens, feral and possessive. His magic thrums with power he’s never felt before, taking form as a magnificent knot at the base of his dick.

_“Breed her. Take her.”_

A snarling growl emanates from above you accompanied by a particularly hard thrust. It vibrates his entire body and alights you with satisfaction. You faintly feel your soul being pulled loose as it closes in on Sans’s, floating in front of your faces.

That fat knot slaps against your cunt, threatening to breach you. This is something completely new for both of you, but it only serves to heighten this craving as you imagine that thing inside you.

“Oh fuck yes!” Colors flash and blur as your souls grind against each other. You two are too lost to notice the blending of soul magics as your peaks are reached.

_“Mine, all mine!”_

A feral snarl roars above you as that bestial knot is plunged into your eager hole, firmly tying you two together. You scream out his name as he slams and holds his pelvis against you, clamping down his dull canines into your neck. The sharp pains of breaking skin and delightful feeling of being stretched to capacity sends you spiraling over the edge as you shudder underneath him. His dick shoots rope after rope of thick, sticky, magic inside you.

“ _All of it, take ALL of it!”_

You grind your ass against him, welcoming each new blast of monster seed with a moan. It sparks and cools the incessant burning of your loins as it flows deeper, pooling in your womb. Your walls squeeze and twitch around him, only encouraging him to release more. There’s just so much as it soon starts leaking around the knot and down your thighs, clinging to you, unwilling to leave.

Your souls return to their respective bodies and Sans groans as a particularly large burst of cum is added to your union. Carefully removing his teeth from your neck, he rolls off of you onto his side, keeping you close and burying his head into your back. The arousal slowly dulls, but never completely fades as your connection persists into the night. Awakened again by a gentle nudging of hips trying to get closer, deeper as your body tries to absorb the abundance of magic needed to support the child you’d conceived. You spend the night wrapped in each other’s’ embrace, murmuring “I love you” and sweet nothings to the other until you both fall asleep. Each holding one hand on your stomach where a newfound soul glows happily.

 


End file.
